feat: integrate Tailwind CSS and enhance MainForm component

- Added Tailwind CSS and related packages to the project.
- Refactored App.css and index.css to use Tailwind for styling.
- Enhanced MainForm component with improved form handling, validation, and layout using Material-UI and Tailwind CSS.
- Implemented dynamic error handling and submission feedback.
- Created a new Tailwind configuration file.

frontend/package.json

@@ -21,7 +21,11 @@
     "react-dom": "^19.2.0",
     "react-i18next": "^16.2.0",
     "react-router-dom": "^7.11.0",
-    "styled-components": "^6.1.19"
+    "styled-components": "^6.1.19",
+    "tailwind-merge": "^3.3.1",
+    "tailwindcss": "^4.1.11",
+    "tailwindcss-animate": "^1.0.7",
+    "@tailwindcss/vite": "^4.1.11"
   },
   "devDependencies": {
     "@eslint/js": "^9.39.1",
@@ -37,4 +41,4 @@
     "typescript-eslint": "^8.46.4",
     "vite": "^7.2.4"
   }
-}
+}